Gas hammer



June 8, 1937. 'T. c. GRAY 2,083,261

, GAS HAMMER 'F'iied March 7, 1936 v 2 Sheets-Sheet 1 June 8, 1937. T.c. GRAY 2,083,261

GAS HAMMER Filed March '7, 1936. 2' Sheets-Shem; 2

-. Patented June 8, 1937 PATENT OFFICE GAS HAMMER Thomas 0. Gray,Evanston, 111., asslgnor to Barco Manufacturing of. Illinois 00.,Chicago, 111., a corporation Application March '1, 1936, Serial No.7.593

11 Claims.

This invention relates to improvements in internal combustion hammers.

Heretofore internal combustion hammers having springs for returning thepistons have had such return springs mounted inside of the cylinderbelow the piston. The springs so located are subject to considerable ofthe heat generated.

in the cylinder by combustion and are therefore liable to deteriorate byreason of the effect of such heat. Furthermore, the return springs soconfined are not conveniently accessible for replacement. Anotherdisadvantage of such an arrangement is that the confining of the springin the cylinder below the piston necessitates pro- 5 viding a cylinderof considerable length.

In accordance with this invention the piston return springs are mountedoutside of the cylinder,.thus making them more accessible, easier tokeep cool, and making it possible to employ 20 a shorter cylinder.

Various other objects and advantages of the invention inherentlypossessed by it wil1 become apparent upon a perusal of thespecification.

' In the drawings:

Fig. 1 is a central vertical sectional view of one form of theinvention, and Fig. '2 is a central vertical section of another form ofthe invention.

Referring now to Fig. 1, the invention therein 30 shown includes acylinder l in which a piston 2 is disposed. The piston is provided witha striking portion 3 adapted, at the lower end of the stroke of thepiston, to strike the raised portion 4 of an anvil 5 which transmits theblow to a 5 tool 6 extending upwardly into the anvil. While a recess isprovided in the anvil shown to receive the tool, it should be understoodthat a recess is not necessary as the bottom of the anvil may beotherwise shaped in the area in which it 40 contacts with the tool. 1

The tool, which may be a drill, tamper, concrete breaker, or othersimilar device, is retained by a tool guide I, abutting the lower end ofan anvil housing 8 andheld yieldably thereagainst 45 by tension springscarried on tie rods whose upper ends are supported preferably on thehandle ring, later described. These springs and tie rods may be similarto those disclosed in U. S. Letters Patent No. 1,997,072, issued April9, 1935, 50 to James A. Mould.

In hammers of this type heretofore constructed, the piston returnsprings have been positloned within the cylinder below the piston,usually between the piston and the anvil. The present inventioncontemplates mounting the return springs outside of the cylinder. withthis end in view, a rod 9 is connected inany suitable mannerto the upperend of the piston and extends through the top of the cylinder, beingprovided on its upper end with a head I I or some other suit-' ablemeans for retaining the upper end of the return spring 12.. The lowerend of the spring i2 is preferably seated on another spring which may betermed a cushioning spring l3, being heavier and stronger than the longspring and serving to dampenthe vibrations of the longer I spring. Theshort cushioning -spring surrounds a boss M on the top' of the cylinderand is held against lateral displacement thereby.

The head. ll reciprocates in a guideway I5 which may be either acylinder or of other suitable construction to guide and steady the rod 9in its movements, and also to form a protective guard around theenclosed moving parts. The cylindrical guideway l5 of Fig. 1 is providedwith a cover plate l6 having a central aperture through which a tool orrod may be introduced to depress the head and the piston for startingpurposes. A keyway l0 cooperating with a key 20 prevents rotation of thehead.

While other means of controlling the ignition for the hammer may beemployed, it is preferred to operate the timer or interrupter from thehead II which, for this purpose, is provided with a cam surface l8 atone side. As the head reciprocates with the piston, the cam follower 19will press the plunger 2| outwardly to cause a spark across theterminals of the spark plug 22. During normal operation of the device,the piston will not rise as high as the position which it occupies inthe drawings because of the resistance offered by the combustible chargein the cylinder above the piston.

The anvil housing and anvil contained therein serve to close the bottomof the cylinder and afford between" the bottom of the piston and top ofthe anvil and housing a precompression space in which the combustiblemixture will be comready to be compressed by the piston when the returnsprings raise the latter up again to firinner walls are shaped to avoidcontacting the' vertical fins such as 29, 3| and others, not shown,which are provided onthe cylinder. The exact manner of mounting thistank and the form of the-carburetor employed for forming the mixture donot constitute a part of this invention, but reference may be had to theJames A. Mould U. 8. Patent No. 1,997,072, issued April 9, 1935, for adisclosure of one suitable form of mounting for the tank andconstruction of a carburetor. It is sufficient to call attention to thefact that the combustible mixture will preferably be introduced into theprecompression space through an aperture 32.

, Also the manner of securing the anvil housing rigidly on the bottomofthe cylinder and the manner of yieldably supporting the tool guide 'Ialso do not constitute a part of this invention. And again reference maybe made to the abovementioned Mouldpatent to ascertain how this may bedone, if desired. It will be noted that in that patent the tension rodswhich retain the anvil housing and'also yieldably support the tool guideare themselves secured upon the handle ring and they may be so supportedhere.

The handles 33 and 34 by which the tool is held are secured to a handlering generally designated as 35 which rests upon a shoulder 36 providedon 35 the cooling iin structure, This handle ring may be secured uponthat shoulder in any suitable manner, for example, by the tension boltsjust above referred to.

Fig. 2 shows another form of the invention,

40 differing from Fig. 1 only in the manner of op-' erating the timingmechanism. The details of. construction of this form of the invention,insofar as they resemble the form disclosed in Fig. 1, need nottherefore be described. It suffices to state that this form of theinvention includes a cylinder 4|, a piston 42, a rod 43 connected'in anysuitable manner to the top of the piston, return springs 44 and 45, anda head 46 secured in any suitable manner, as by threads, to the top ofthe 50 rod for holding the return springs under compression, asillustrated. In this form of the invention, the head 46 is not employedto actuate the timing mechanism.

The piston 42 is provided with a striking portion 41 which imparts theblow of the piston to the I anvil 48 which transmits the blow then to.-thtooi 49.

A timing plunger II having a cam follower I2 riding in a groove- 53 onthe outside of the piston wall will be thrust outwardly by the camsurface 54 provided at the'lower end of the groove to cause a spark to.occur across the terminals or the spark plug II. By removing the coverplate 56 and the spring retaining head 46, the return springs may easilybe replaced whenever desired, and the tension of the springs may beregulated by adjustment of the head on the rod or by the employment ofThe cylinder I'l operates as does the cylinder xmllgofligi 1, both as aguide for the spring retaining head'an'd also as ashield surrounding thev 'It iscontemplated that the fuel tank Ql will 7" be mounted .cntheanvil housing 69 in the or similar manner as is the fuel tank of Fig. 1,the fresh charges of fuel being-"admitted into the precompression spacebelowthe' piston through an aperture 5|.

It should be understood that the drawings and specification. discloseand describe merely two embodiments of the invention, but other varla--tions of the invention are possible andare contemplated and includedwithin the scope of the appended claims.

a The invention above shown and described is claimed as follows:

1. In an internal combustion power hammer, a cylinder, a piston therein,a spring mounted outside of the cylinder, and means operatively cononsaid piston.

2. A power hammer comprising a cylinder and a piston therein, a springmounted outside of 'the cylinder, and means operatively connected withthe spring and with the piston for retracting the piston in the cylinderafter each powerstroke, said means comprising a longitudinally movablerod on said piston.

3. In a power hammer, a cylinder and a piston therein, a spring mountedoutside of the cylinder and substantially coaxial therewith, and meansextending through a wall of the cylinder connected with the piston andoperatively connected with the spring for moving the piston in onedirection, said means comprising a longitudinally movable rod.

4. In a power hammer, a cylinder and a piston therein", a spring mountedoutside of the cylinder, and means extending through one end of thecylinder connected with the piston and operatively connected with thespring for moving the piston in one direction in the cylinder.

5. In a power hammer, a cylinder and a piston therein, a spring mountedoutside of the cylinder, and means extending axially through said springand operatively connected to one end thereof and further connected withthe piston for moving the piston in one direction in the cylinder.

6. In a power hammer, a cylinder and a piston therein, a spring mountedoutside of the cylinder, means operatively connected with the tontherein, a rod connected with the top of the piston extendingthrough'the top of the cylinder, a spring mounted outside of thecylinder operatively connected with said rod and held under compressionthereby, an ignition system for lgniting a combustible mixture in thecylinder, and means connected withsaid rod for controlling the spark insaid-system.

9. In a powerhammer, a cylinder and a piston therein, a rod connectedwith the top of the piston extending through the top of the cylinder, aspring mounted outsideof the cylindenmeans connected with said rodholding said spring under e,oss,ae1 3 compression, and means for varyingthe com- 11. In a. power hammer, a cylinder and a pisspression-ot saidspring. ton therein, a spring supported on the top of said .10. In apower hammer. a cylinder and a piscylinder and rising thereabove andadjustable ton therein, a spring supported on the top of means connectedwith said piston and holding said. cylinder and rising theteabove, andmeans said spring under compression for returning the 5 conficted withsaid piston and holding sairL piston after each power stroke. springunder compression for returning the piston after each power stroke.THOMAS C. GRAY.

